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Wrong MAF sensor I think. Please help!!!

J

jonygtp

New member
Ive mentioned this before in a previous post but now its getting serious. My GTX is an 02 and my car has a really rough idle and cuts out like crazy when i get into the throttle. Also im getting the infamous p0171 code. Bank 1 sensor lean. Installed new PCV valve and cant find any vac leaks. So i unplug the maf and the idle smooths out. Still have the cutting out issue upon driving tho. So i figure i have a bad MAF. Come to find out the maf is from a 97,98 yr model. the smaller one w/o the air channel. Ive read that these are year specific and not interchangable. Im guessing someone put an older TB on the car.

My question is this. If thats the case could that be the reason its running so rough. Do you think my PCM isnt communicting properly with it? Would this cause the rough idle and the cutting out? Ive been all over the engine looking for boost or vac leaks, cant find any. Also it has new plugs as well.. The FPR appears to be fine too, no fuel coming from it. Honestly my prob feels like a fuel delivery issue. New Fuel pump and filter too so im really puzzled. Unfortunatley i dont have a scanner to further read the computer for troubleshooting.. I do have a diablo programmer for my duramax that reads some live data on the car. I can see MAF and MAP readings. Tell me what they should be if that would help me trouble shoot any. Also any other input as to what i could check or somehow trouble shoot this prob would be immensly appreciated! im getting sick of having to baby my car around for fear its running lean.
 


The maf sensors aren't that different in the tabling that it would cause this issue. I know this from doing it myself, got sidetracked forgot to program the table and ... months later noticed the table.

It sounds like you have other issues. There is a tube connecting the EGR to the LIM. Pull it out and look at it where it meets the LIM. Pull back the piece that holds it to the lim and see how big the crack is...
 
thanks billboost ill give that a try. My next guess was going to be a bad LIM but hopefully an easier fix than that
if the tube is cracked what are some ways to fix it?
 
so let me make sure i understand.u correctly.... i should.just buy a new one? lol got it!
If for some reason the tube is fine what should be my next.point of attack? I cant wait to get this car running
to its full potential. This thing outran a buddies fully modded sho a few weeks back. It wasnt missing.quite so bad back
then but still was running rough. So I KNOW THIS THING HAS GOT SOME BALLS UNDER THERE SOMEWHERE
 
Well...we could go into what type of fuel you are using, spray it down with carb/tb cleaner at any vacuum points. Replace any lines that are bad. Clean the TB, are the LIm gaskets metal or plastic, when was the last tune up... keep in mind I jump thread to thread faster than I drive.
 


I did notice a slight change in the rpm when i was spraying some cleaner in that area the other day. i thought maybe my tb gasket was bad but it might have been pulling into the crack in that pipe possibley I think were prob on to something. lll update tomorrow after ive had a chance to pull it out and look at it.
 
The reason I wanted you to pull the tube is that typically, you can't spray enough around it to get an rpm difference, not matter how hard you try.

I'd say you have a TB gasket leak as well.
 
Ok so here's the update so far. Pulled the TB and yes the gasket was split. I remember tearing it a little a couple months back when i pulled it off to clean it and remove the screen. In hind site and after further reading im wishing i would have left it in there. But i know that isnt my major prob here. Is it? IF it is pulling air in after the maf what issues could that cause?

The EGR tube was just fine. Inspected it very closely couldnt see any signs of splitting. I do see signs of grey rtv silicone between the s/c and lower intake. WTH! Who does that? Considering some of the other shoddy work ive seen done on this car i wouldnt be surprised if the intake is leaking. It doesnt look to have the good LIM gasket so Im gonna go ahead and pull the s/c and intake off and just make sure its done right this time. Plus this will give me a chance really go over the engine and clean it up, replace some of the brittle wire loom and oher little things like that. I want the engine bay looking sharp.

So by taking the intake gaskets out of the question are there any other things i should look for? One thing i did see was around two of the rear injectors it is always damp around where they go into the engine. All the other have stayed dry. Does this indicate bad injector seals? Also how do i check to see if the injector themselves are good?

So change intake gaskets; check out the injectors; New seal on the TB; Im gonna put wires on it. What type should i get? keep in mind my budget is pretty small and i want to run a 3.4 pulley.
The plugs I put in a few weeks back are Bosch Iridium 106s. Are these ok to run a 3.4 with?

Ok that pretty well brings us up to speed. I know its a lot of ??? But the help is greatly appreciated :) Thanks so mch for being patient with me. Chime in with your seeds of gtp knowlegde as you can. I really hope to have the car back on the road by toomrrow night
 
Delco or Autolite wires.

Take those ****ty bosch plugs out.. That could be your problem.

Replace the injector o rings, top and bottom. The intake gasket kit will come with them..

The intake kit part number you want is felpro# MS-98014t
 


ok thanks for the input. are these items i can get from a parts store? The car had 7mm wires on it. What size should i get?

The plugs i bought came pregapped but didnt check them cause i didnt have my gap tool. what is the gapping supposed to be?

any idea what that felpro kit costs?
 
All is bought at the parts store.

Gasket kit will be about 45-50 I think.. Can't remember right now..

Bosch plugs run like **** in these cars. Get either the Delco iridiums or Autolite iridiums if you don't wanna change the plugs for a very long time. Or get coppers.
 
Gasket is $75 not $45-50, the $45-50 is the plastic gasket.
Does your car have headers? If not I would not run a 3.4 pulley on that car.
 
Gasket is 45-50 if you use discount codes or buy online. I had a Regal guy stop over the other week...his $235 LIM swap budget went down to a little over a 100 and we added in SC gasket and TB gasket (kinda need them..lol)

Go onto Advance's online site and start putting stuff in your cart, when you get to 90 stop. Use code Huge30 and you'll see 30 pop off it. Print. Clear the basket and do it again or use lesser codes, like 20 off 50 etc. You'll take those to the store and they'll match it for ya.

Any Bosch plugs are bad in our engines after as little as a couple weeks. They don't stand up to our waste spark systems well. Personally, I'd say get copper plugs, because you'll be in there more often. Plus iridium plugs still have the gap expand like coppers. So you'd want to regap at times.
 
Great info guys. Especially on the discount codes. Thanks Billboost! Gonna get some parts and Ill check back in later with another update
 


i did my lim gaskets on the super cheap, 60 for all parts, and that included new vac lines and T's. <<<you'll want to pick 2 T's and about 3 feet of vac line, one or all of the rubber T's are bound to break on you.

i got just the lim gaskets for 42 shipped from rockauto

had 20 in credit on my AZ card, so that covered 20 bucks worth of coolant and the sc gasket. listed as a upper plenum gasket, fyi, or you'll never find it. laid out around 5 bucks in all after my credit.

5 bucks on vac tube and T's, and another 5 on some lower O rings for the injectors. and another 5 for coolant elbows.

i left my tb gasket and t stat gaskets on the SC and lim. saved a few bucks.

and dont waste your money on that 50/50 antifreeze, buy full strength. one gallon should cover the job.

all in all with some smart shopping, dis codes and all, you can do this for under $100.00


dont forget to get thread sealant for the lim bolts as well.


and i loaded at least 4 shopping carts with codes and all before i bought a thing, just to see which co. would be cheapest all around.

you need to watch for rockauto and the double shipping cost, due to orders coming from different warehouses, the lim gaskets came from one location, the rest from another, thus adding 6 bucks to the order. so i only got the lim gaskets, and sorced the rest local and free like lol
 
Or you could check out the common parts thread and you'd know off the top of your head it's like MS95744 (I think...)
 
advances web site must be screwed up right now.. I type in the part # but thats all itll let me do. cant click on anything after that
Gotta love tech sometimes
 
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